[Problems of early detection of neoplasms from an epidemiological point of view].

Based on the epidemiologic literature, the problem of mass cancer screening projects is discussed. In the case of breast cancer the evidence for a reduction of mortality in the age group over 50 seems conclusive, whereas the specific role of mammography is still controversial. At present, no routine mammographic screening should be undertaken in women under 50 years of age. There is presumptive evidence that routine proctosigmoidoscopy for early diagnosis of cancer of the large bowel reduces mortality. However, this method seems of doubtful practical value for financial and psychological reasons. There is reason to believe that improvement in colorectal survival rates may be expected with widespread use of the "Hemoccult" test. Routine screening for cervical cancer should be continued, although the epidemiological evidence of its value is only circumstantial. In the case of lung cancer, there is not much hope that secondary prevention will improve mortality rates. Earlier detection of prostatic cancer by means of digital examination may eventually improve mortality rates, but at present the evidence is lacking.